Within the past thirty years, researchers have found strong evidence
linking genes and disease. The development of predictive genetic tests
followed shortly after the isolation of certain candidate genes. Although
predictive genetic screening is only available for a handful of diseases,
its effects and ramifications have become hotly debated issues in a wide
range of areas, from government to religion. The debate began in the 1993
when researchers isolated the BRCA1 gene, which is associated with increased
risk of developing breast and ovarian cancer. The discovery of this gene
led to excitement and speculation of developing a predictive genetic test
to identify those women at risk for these cancers. In this paper, I will
first describe the biology of genetic testing, and then discuss the pros
and cons of predictive genetic testing.

Before we start discussing how genetic tests are developed, let us discuss
how genes can trigger disease. A sound body requires the action of many
proteins working together. For a protein to function properly, an intact
gene must encode for that specific protein. A mutation describes a gene
which has been changed. The most common type of mutation is a single change
of a nucleotide of DNA. Other types of mutations include the loss or gain
of a nucleotide and the disappearance or multiplication of long segments
of DNA. Mutations can have three effects: beneficial, harmful, or neutral.
Mutations are beneficial if the fitness of an individual is enhanced. Harmful
mutations can either slightly alter a protein, where the protein may still
minimally function, or they may totally disable a protein. In this instance,
the outcome is not only based on how a mutation alters a proteinís function,
but on how important the protein is to the body (Understanding Gene Testing).

Since we have determined how genes can trigger harmful effects in the
body, we can now examine how scientists look for specific genes that cause
diseases. Scientists, looking for a diseased gene, study DNA samples in
individuals where the disease has been present in the family for many generations.
They look for specific genetic markers, which are DNA segments that are
identified in individuals with the disease, and not identified in healthy
individuals. Scientists then narrow down the area of DNA by mapping a gene.
If a disease gene is mapped to an area, then the genelike sequences become
candidate genes for a specific disease gene.

The opposite may also result; the expression of sequenced genes in the
tissue may suggest a disease gene. If scientists can determine the map
position of a known disease gene, than the unassigned genes in that region
may be candidate genes. Once candidate genes are selected, scientists then
look for mutations in those genes. They can identify these specific regions
by constructing DNA probes, which are single strands of DNA that line up
with parts of a known gene. The probe, tagged with a radioactive atom,
binds to the complementary bases. The area that the probe binds to will
light up, allowing scientists to carefully examine that specific piece
of DNA for any mutations. Scientists follow the previous steps to develop
predictive gene tests (Understanding Gene Testing).

Predictive gene tests will tell an individual whether or not they have
a disease-related mutation. An inherited mutated gene is carried in the
reproductive cells. Therefore, the mutated gene will be present in cells
throughout the body. Predictive gene tests can detect the mutation in white
blood cells. If the mutation is present, the person must be told that a
variety of factors will determine if the disease will develop. Most individuals
who carry the familial adenomatous polyposis gene will ultimately develop
colon cancer. On the other hand, women carrying the BRCA1 mutation have
an 80% chance of getting breast cancer by the age of 65. Theses women also
have a 20% chance of remaining free from breast cancer throughout their
lives. Even those individuals who donít have an inherited mutation are
still at risk for diseases, because other factors are involved.

Predictive gene tests are available for a number of diseases at the
present, and many more are currently being developed. Diseases like Tay-Sachs
and cystic fibrosis now have predictive gene tests. Within the family of
cancers, genes have been found for 1) retinoblastoma, a childhood eye cancer,
2) Wilmsí tumor, a kidney cancer which attacks children before the age
of five, and 3) Li-Fraumeni syndrome, which attacks children and young
adults with an assortment of cancers. Recently, gene mutations have been
linked to colon and breast cancer. Inherited forms of these cancers account
for 5-10% of all cases. Although this number appears low, an estimated
1 in 300 women carry inherited mutations of the breast cancer gene. According
to experts, this estimate also pertains to colon cancer cases. Most individuals
who develop colon or breast cancer donít have inherited gene mutations.
Rather, these individuals acquire mutations, which lead to cancer.

Although other genetic mutations have been identified before BRCA1 and
BRCA2, it wasnít until their discoveries that much of the public began
to take notice of these scientific breakthroughs. Scientists have high
hopes for the results of the discoveries of these two genes. They hope
that theses new genes will 1) increase the understanding of deadly cancers,
2) lead to effective therapies, and 3) identify those individuals at risk
(Kahn 1996). In January of 1996, OncorMed, Inc. offered the test for the
detection of the BRCA1 gene to consumers. Itís been almost two years since
this predictive test became available to the public and since that time
other tests have become available. These predictive gene tests have prompted
a public controversy. Should genetic testing be made available to the general
public? Why or why not? Letís take a closer look at the arguments from
both sides.

The proponents are up first. These individuals believe that persons
from high risk families can gain many benefits from knowing whether or
not they carry a genetic mutation. For instance, a negative test that is
strongly predictive can reassure a person and provide relief. A negative
test can also eliminate the need for continued checkups and tests, like
a colonoscopy, which is routine for individuals from high risk families.
Proponents also point to a number of benefits from positive test result.
1) It relieves uncertainty, 2) it allows a person to begin making decisions
about the future. If the test indicates that a person will definitely develop
a disease, the person can begin to prepare for that time. 3) Under the
best circumstances, a positive test result can lead to counseling and intervention
to help reduce the risk of developing that disease. For example, the earlier
that colon cancer is detected, the greater the chance of survival. 4) A
positive test warns a person to continue checkups, and to maintain or begin
to engage in a healthy lifestyle (high-fiber, low-fat diet, and regular
exercise). 5) A positive test result gives the person the option of having
surgery to remove that organ that is at risk for disease (Understanding
Gene Testing).

Opponents to predictive genetic testing point out many problems that
have already resulted or may result from these tests. For one, they argue
that uncertainty is not really relieved by these tests because they do
no indicate whether or not the person will develop the disease, and the
time frame that the disease could occur. They also point out that the person
who receives a positive test result may become obsessed with worrying.
Nancy Wexler, a clinical psychologist from Columbia University, states
that some people may "end up hospitalizedónot for the disease, but
for depression. Even a negative test result can create problems, when a
test suddenly removes the specter on which a whole life has been organized"
(Time 1996).

Even doctors point out the problems of genetic testing. These tests
may often produce false-positive or false-negative results. Negative results
can give a person a false sense of security. Just because a person has
a negative test result to a specific gene mutation doesnít mean that they
will not develop cancer, or another disease from other environmental or
genetic factors. For example, women without the BRCA1 mutation still have
a 12% risk of developing breast cancer, which all women face. Opponents
also argue that consumers donít understand the meanings of the test results.
Many people are not aware that these tests only indicate the risk of developing
a certain disease. Education and counseling are necessary, but there is
currently a shortage of these specialists. Therefore, doctors not trained
well in genetics are vulnerable to malpractice suits by giving out faulty
information, no information, or not referring to a genetic specialist (Newsletter
1997).

Before I researched this topic, I had a general idea about genetic testing,
but I did not realize exactly what issues people were discussing. I believe
I have a much better understanding of the pertinent issues that are being
debated about predictive genetic testing. After reading arguments from
both sides, I have concluded that genetic tests do not provide a person
with definitive results and therefore should not be used. I believe they
do set up people with false hopes and possibly a false sense of security.
In the articles I read to prepare for this paper, numerous examples were
given of people belonging to high risk families who believe that genetic
tests are not the answer.

Besides the reasons I stated given by opponents,family members also
are concerned about discrimination from employers and insurers. I thought
we are trying to end discrimination. Genetic testing only gives people
more of a reason to categorize people into certain groups. Morally and
ethically, I believe that genetic testing should not be performed if treatments
are not available for that specific disease. What do we tell those people
if they do test positive? "Well, sorry, we canít help you, but weíll
let you know if a treatment becomes available." This seems rather
shallow to me. And most predictive genetic tests cannot even definitely
tell a person whether or not they will develop the disease. Genetic tests
are here and available to consumers for a number of diseases, whether we
like it or not. We cannot ignore their existence. The best thing we can
do for consumers is to educate them about the pros and cons of predictive
genetic testing and let them make the choice. Life is a series of choices
and we need to embrace those choices. However, we must be able to live
with the consequences of these choices.

References

Do you want to know if the news is bad? Time. Fall 1996. V148. N14.
P29(1).